Implantable medical devices (IMDs) are devices designed to be implanted into a patient. Some examples of these devices include cardiac rhythm management (CRM) devices such as implantable pacemakers, implantable cardioverter defibrillators (ICDs), and devices that include a combination of pacing and defibrillation. The devices are typically used to treat patients using electrical therapy and to aid a physician or caregiver in patient diagnosis through internal monitoring of a patient's condition. The devices may include electrical leads in communication with sense amplifiers to monitor electrical heart activity within a patient, and often include sensors to monitor other internal patient parameters. Other examples of implantable medical devices include implantable insulin pumps or devices implanted to administer drugs to a patient.
Congestive heart failure (CHF) is a disease that reduces the ability of the ventricles of the heart to contract or relax. This results in an inadequate amount of blood being pumped into circulation. The reduced ability to move blood from veins to arteries may increase volume and pressure within the heart leading to heart failure progression. If left unchecked, CHF can lead to death. Respiratory function of a patient changes as the disease progresses. Monitoring aspects of respiration, such as the lung tidal volume, gives an indication of the progression of the disease.